Stage IV adenocarcinoma lung cancer

My mom was recently diagnosed with stage 4 adenocarcinoma lung cancer. I brought her into the hospital last week because she had swelling in her face and shortness of breath. They found several masses in her right lung, one of which is causing svc syndrome. The mass is pushing on her superior vena cava causing the swelling in the top half of her body.  She also has fluid in her lungs and in her pericardium. The doctors immediately started radiation on the mass causing the svc syndrome, at the time the doctors believed it was small cell lung cancer. After the surgery to drain the fluid results came back on the tissue sample confirming it was non small cell lung cancer. From that point she had an MRI, CT, and bone scan. Results came back that there were between 5 to 7 masses in her brain, one on her pelvic bone, and a small mass on her adrenal gland. Full brain radiation was started as well as radiation on her pelvic bone. At this point the doctors here are telling me she has months and not really giving me much hope. She is currently in the hospital for being so sick but as soon as she has a discharge date I will be taking her for a second opinion. I'm scared and questioning why something like this could happen. She and I both have plenty family and friends supporting us but to have support from others who have gone or are going through this would be tremendous. Im scared and don't know what to do at this point.